Means for cutting adits in chalk and allied strata



Sept. 26, 1944. G, GARDNER 2,359,213

MEANS FOR CUTTING ADITs IN CHALK- AND ALLIED STRATA Filed NOV- 20, 1942y p y z2' u (il. 1529.4'

" orneys.

Patented Sept. 26, 1944 MEANS FOR CUTTING ADITS IN 'CHALK AND ALLIEDSTRATA James Geary Gardner,` Caterham, England l Application November20, 1942, Serial No. 466,322 In Great Britain June 17, 1942 3 Claims.262-33) This invention relates to means for cutting adits, channels,galleries or the like in chalk, limestone, compacted Iclay and kindredearth strata.

When cutting operations are commenced upon a face of -chalk or limestoneit is normal to employ pneumatic drills or hammers and outline'a cavityso that the material enclosed by the out can be removed. Thisunfortunately shattersA the rock and loosens the formation for some 12or 18 inches adjoining the cut and if the rock is unstratiiied and innodular form, pillars and walls which might otherwise be used to supportthe roof are useless for such purpose and when galleries are cut forcommunication passages or caves or rooms excavated for war timeshelters, it is frequently necessary to line the parts excavated withbrick, and lin some cases provide pillars or props in addition.

'I'he object of the present invention is to provide means for cuttingthe rock instead of shattering it and so avoid the disruption of theconne wall and further to make a cut that is so clean that the wallsurface produced has a ilat and even surface. With some rocks of theclass mentioned, and especially with chalk there is sufircient waterlatent in the rock and expressed by the percussive cutting operationtoform a slurry of the powdered material flowing from the chisel edgeand the operation of cutting causes the slurry to flow backwards andrelieve the tendency otherwise of the tool to wedge itself in and stick.For rocks that have insufficient latent moisture to form a slurry fromthe cut face, thetool is grooved or drilled and the cut supplied withwater from some suitable external source. In such latter cases water isonly required for the initial or rst two or three chisel incisions, thespace left by the preceding cut or cuts accommodating the swarfmaterial.

The invention consists in means for cutting adits, channels, galleriesor passages in chalk, limestone, compacted clay and kindred earthstrata, without shattering the formation, Whilst providing an evensurface `and comprises a percussive tool having a `long and preferablyslightly tapering and relatively thin chisel or jumper portion, saidtool being deformed lengthwise intermediate its spigot and chiselportion to bring the penetrating blade out to or beyond the connes ofthe power driven percussive device adapted to operate said chisel, andto enable it to be driven forward tinto the rock face and incise by aseries of abutting cuts, a predetermined boundary outline, groovesextending from the hilt to the tip of the blade for thelpassage of waterfor slurryng the powdered rmaterial during the cutting operation. Thepercussive hammer is pro- Vided with a sled for engagement with the wallof the out, thus aligning the offset blade of the tool with such wall,and the hammer tis preferably also provided with a lateral handle forholding the hammer against said Wall as the cutting proceeds.

In order that the invention may be .better understood reference is madeto the accompanying drawing, wherein a' proposed embodiment of theinvention is shown and wherein- Fig. 1 is a side elevation of theoperating tool.

Fig. 2 is a plan of Fig. 1.

Fig. 3 shows the tool in operation cutting an adit or passage in therock face and leaving an even sofiit as cutting takes place.

Fig. 4 is an illustration of the commencement of an adit or gallery witha wall partly incised to a predetermined contour, and a portion of therock material within the incised boundary removed to show the soilit.

Referring to the drawing the cutting chisel or jumper A is adapted to bedriven by a power ldriven reciprocating hammer B, see Eig, 3. The tool Ahas a normal spigot I, a shank 2, which is bent or deformed at 3 andthen straightened and provided with a blade 4, the said blade beingslightly tapered and provided at its operative end with a square cuttingor powdering edge 5 atright angles to the blade 4. A handle 6 is formedintegral with, or attached to, the shank 2, and a groove or grooves 'Iis or are formed at the tool blade shoulder to carry water to thecutting edge. The tool is bent or offset at 3 an amount sufiicient tocarry the shoulders 8 or hilt of the blade 4 to or outside of theconfines of the tool B as shown in Fig. 3.

The method of use and manner of operation is as follows:

If C represents the rock or quarry face the configuration of the adit,gallery or passage ID (see Fig. 4) is marked out as at II and cuttingcommences, and the entire outline incised as at I2 by penetrating therock by a series of successive abutting cuts, the rock at floor levelbeing also undercut as shown at I3. This cutting operation provides asmooth and even soiit or face I4 as shown in Figs. 3 and 4. The rockmaterial enclosed within the incised boundary can be excavated with apickaxe, crowbar or other tool, or the device forming the subject'ofthis invention may be used for intercutting as shown at I5 .in Fig. 3.

of the tool, and allowed to dribble thereupon or down the face of therock above the portion being cut. The water so supplied ndsits wayto thecutting face through the grooves 1 and forms a slurry which exudes atthe rock face. After one or a few incisions has or have been made it isgenerally found that no further water is required, since the powderedrock of successive cuts is driven `or falls into the aperture or slitmade.

by the `prior jcut. YSome rocks carry suflicient moisture to render theneed of further waterV unnecessary( In Ythe operationV of cutting thetool is driven in up to the hilt or shoulder 8 and' i's thenv withdrawnfor the next cut. Should the tooly stick then the operator seizes thehandle 6", and by a combined twisting and withdrawing action jerks thetool backwards and out of its cut,

the tapering of the blade assisting this opera'- tion.

To assist left handed cutting theV power driven hammer B may be providedwith a sled 20, and additional grip 2|, the sled being pushed againstand along the eut walll as driving proceeds.

Should the tool meet int or stone in its penetration, the tool in themajority' of cases will shatter it, but an experienced quarryman willfeel the stone and cut upwards or downwards to avoid it, and leave itsremoval, so as not to injure the surface, until excavation.

The chisel or jumper blade 4` is made of a width of face depending uponthe power capable of being lexercised by a pneumatic or electricpercussion tool. The blade length mayalso vary but an inward cut of 18to 20 inches is a practical depth for the process of excavation.

The 'invention is not limited in itsv scope of application. Thus wellscan be bored of any sectionV or underground chambers cut, railroad orcanal tunnels can be cut in suitable strata such as chalkwithself-supporting roofs having a soflit that appears as if plastered. Iclaim;

1i. A tool for use in cutting adits and passages in 'chalk and likematerials, comprising a flat chisel-shaped blade having a square cuttingedge and-'of tapered section from hilt to tip, a spigot for attachmentto a power percussion hammer, an offset portion intermediate the spigotand the blade, grooves extending from hilt to tip forY the passage ofwater, and a handle extending at right angles to the length of the tool.

2. A tool according. to claim I, in combination Wth'a percussion hammerhaving a sled for wall engagement and alignment.

'3. Atool according to claim 1, in combination with a percussion hammerprovided with a sled for wall engagement and alignment, and with anadditional lateral handle for left hand cutting.

JAMES` GEARY GARDNER.

